1. Field of the Invention
The invention concerns a procedure for shifting a transmission composed of several gear units, where a first gear unit, e.g., a reduction gear unit, is connected to an engine and a last gear unit, e.g., a range gear unit, is connected to an output shaft for a driven part, in particular wheels, and where between the first and the last gear unit at least one second gear unit, e.g., a speed change gear unit, is provided.
2. Description of the Related Art
U.S. Pat. No. 4,318,305 (Wetrich et al.) teaches a transmission having several gear units. A first gear unit provides either direct drive or a speed reduction and can be shifted hydraulically. A second gear unit is a speed change gear unit which can be synchronized and shifted mechanically. A last gear unit is arranged on the output shaft and forms a range gear unit which can be shifted mechanically, but is not synchronized. Each gear unit can be shifted independently of the others, so that a large number of gear ratios can be obtained.
This transmission arrangement can be improved since it does not permit simple shifting of the last gear unit, that is, the range gear unit, because it does not have synchronizers. Unfortunately, due to the large rotational inertia ahead of the range gear unit, very large synchronizers normally would be required to provide synchronized range gear shifting. The problem underlying this invention is seen as providing the possibility of shifting the range gear unit easily and rapidly, but without the expense of adding large synchronizers.